JPS5938290B2 - Improvements in copper precipitation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the precipitation of copper from aqueous solutions, particularly but not exclusively as applied to the recovery of nickel from nickel mattes by chlorine leaching.

Note that all percentages in this specification are by weight.

Leaching nickel from the matte by contacting the matte slurry with chlorine is a convenient first step step to obtain a nickel-containing solution from which the purified nickel product can be recovered after purification, e.g. by electrowinning. be.

A particularly effective operation for dissolving substantially all of the nickel present in the matte without dissolving the undesirably high amounts of sulfur present ensures solubility of the cuprous ions. for copper and sufficient chloride ions,
The mat is subjected to the action of chlorine, typically in the presence of an aqueous solution containing 100 grams per liter (9/IJ) or more.

In such a method, the reaction involves matte and a second in solution.
This is thought to occur with copper ions, and chlorine helps regenerate cupric ions.

Such operations are known, and more recent improvements include the addition of redundant redundancy during leaching to achieve selective dissolution of some of the metals in the matte.
dox potential) is described in Canadian Patent No. 967,009.

At the end of leaching, it is generally necessary to reduce the level of copper dissolved in the nickel-containing leaching solution so that subsequent purification and electrowinning operations can be carried out effectively.

One well-known technique for reducing the copper content of solutions consists of precipitation with elements less base than copper.

The use of elements such as iron for this purpose has the undesirable result of introducing impurities into the solution which must then be removed, whereas the use of elemental nickel for purposes such as those mentioned above often costs.

A commercially viable proposal involves the use of mats for precipitation.

In US Pat. No. 2,180,520, a copper-nickel solution is treated with a copper-nickel matte to make the copper precipitation more effective.

The recommended mats are those with relatively low sulfur content;
That is, the sulfur content of the matte is at most % of the copper content.

Other precipitation methods are described in British Patent No. 1378053 (corresponding to Canadian Patent No. 967007).
(with amendments during the UK application process), which involves treating a nickel-copper solution with a combination of elemental sulfur and a matte in which the atomic ratio of nickel to sulfur is greater than 1.

In one embodiment of this specification, the nickel-copper matte is leached by passing chlorine gas through a boiling aqueous solution of the matte so that 85% of the nickel present is dissolved and approximately 2.
A solid residue containing part 0 elemental sulfur and a solution containing 50 &/l dissolved copper are removed.

By contacting and stirring this residue with this solution without passing any further chlorine, a small amount of the dissolved copper is precipitated, thereby reducing the copper content of the solution to 41 g/l.

The remaining copper is removed only by reaction with fresh nickel matte added to the slurry, where the atomic ratio of nickel to sulfur is greater than 1.

The present invention is based on the finding that nickel matte can be effectively used as a precipitant for copper by leaching a portion of its nickel content without the formation of elemental sulfur.

The reason why nickel mattes activated by partial leaching have improved precipitation properties is not known in detail.

However, whatever the mechanism, the following surprising things have been discovered.

That is: (a) the efficiency of precipitation obtained with a given mat, as determined by reaction kinetics, for example, is greatly improved by partial leaching; (b) the addition of sulfur to the mat results in effective precipitation. and (c) partially leached nickel mattes, whether or not the atomic ratio of nickel to sulfur therein is greater or less than 1, may be used as a means for precipitation of copper. Can be used effectively.

That is, the present invention leaches 15-60% of the nickel from the matte by reacting a mud slurry in an aqueous solution containing copper ions with gaseous chlorine, and then contacts the partially leached matte with further gaseous chlorine. This is a method in which copper is precipitated from an aqueous solution by means of a nickel mat, which is brought into contact with the solution in which the copper is precipitated without causing any precipitation.

Chlorine serves as an oxidizing agent to generate cupric ions from cuprous ions inexpensively and without the introduction of undesirable external ions into the solution.

It is important in the present invention to partially leaching 15-60% of the nickel from the matte.

That is, if the partial leaching of nickel from the matte is less than 15%, sufficient activity of the matte cannot be obtained, while if it exceeds 60%, elemental sulfur is produced, which is not desirable.

The matte activated by partial leaching in this manner is particularly advantageous for the removal of copper from nickel-containing solutions obtained by chlorine leaching the nickel matte.

In such a method, the solution to be treated with the activated matte is a copper ion-containing aqueous slurry of the nickel matte containing at least 109/l of dissolved copper to dissolve all or part of the nickel from the matte. It may also be produced by contacting with chlorine.

Mats that are partially leached and then used for precipitation are
Conveniently the nickel will be the same raw material from which it is recovered.

However, this is by no means essential and other suitable nickel mattes may be used for partial leaching and precipitation.

More preferably, the matte is slurried with an aqueous copper ion-containing solution containing at least 10 g/13 copper, and chlorine is introduced into the slurry so that 15 to 60 parts of the nickel in the matte is transferred into the solution; By ceasing the chlorine introduction, keeping the partially leached matte in contact with the nickel- and copper-containing leaching solution to allow the copper to precipitate out of solution, and separating the precipitated copper and leaching residue from the solution, In order to obtain a method of recovering nickel from nickel matte, the same matte is used and the leaching and precipitation steps are combined.

If desired, the mat may be leached in two or more parts during chlorination.

For example, a first portion of the mat may be fully leached and the next portion may be added thereafter to effect only partial leaching.

The most preferred nickel recovery method, which involves continuous leaching and precipitation reactions resulting from the addition of a single matte to a copper-containing solution, reduces the extent of leaching, i.e. the duration of chlorination, to the matte that remains when the chlorine flow is discontinued. The amount should be selected to ensure that the amount is at least sufficient to reduce the amount of copper in the solution to the desired level.

Chlorine leaching of the matte, whether performed for complete dissolution of the nickel to be recovered or to form a partially leached matte for use in copper precipitation, also eliminates the presence of copper ions. It is necessary to do this with

This is to ensure effective leaching of nickel while minimizing sulfate formation.

In practice, at least 1 (Di'/111 preferably 30
I/11 or more copper should be present in the solution in which the nickel matte is slurried.

Although it is convenient to discuss the leaching and precipitation steps separately, both steps actually occur simultaneously when chlorine is bubbled through the mud slurry.

Precipitation can thus be considered as part of the reactions that can occur during chlorine leaching.

Since precipitation associated with the leaching process reduces the level of dissolved copper, it is necessary to select the initial level of copper in the solution according to the composition of the matte to be leached.

For example, if the sulfur content of the nickel matte to be leached is on the order of 20 parts, then 30-40 &/1. It is desirable to have a copper level of .

The leaching reaction can be carried out at a low temperature of about 60°C,
Preferably the mud slurry should be maintained at 90-110°C.

Temperature can generally be maintained by the exotherm of the leaching reaction.

The novel copper precipitation using partially leached nickel matte is most applicable to all improved methods for recovering nickel from impure nickel matte.

The method for recovering nickel in quantity according to the present invention consists of the following steps: (1) Slurrying the impure matte with a copper-containing aqueous solution and partially leaching it with chlorine; , allowing the partially leached matte to precipitate the copper from the leaching solution: (IIIl) separating the leaching solution from step (II) from the solid consisting of precipitated copper and matte residue; leaching solution of iron, copper,
Purification by solvent extraction and/or ion exchange to remove impurities such as cobalt, arsenic, lead and bismuth; (V) step (subjecting the purified solution from the leap to electrowinning to recover pure nickel); , and also in step (1) above and in the next step (VB, generating chlorine for recirculation for leaching of the matte; (Vll) slurrying the solid from step (In) with the spent electrolyte from step (■); treated with chlorine to have complete leaching of the solids, thereby resulting in a copper- and nickel-containing solution which is circulated to carry out step (I) on fresh pine and a residue consisting essentially of sulfur. let

To ensure complete leaching efficiency of the process (Vl), a portion of the copper and nickel-containing solution obtained in the process is internally heated to a predetermined level of dissolved copper at the beginning of this complete leaching. circulate.

Examples are shown below.

Example 1 A partially leached mat was prepared as follows.

200 g of granulated matte having an analysis value of 0.8% Nickel Ni, 0.54% Copper, 1.48% Cobalt, 0.38% Sulfur, 26.4% Sulfur, by weight,
9/1. of nickel and 309/l of copper at 90°C with a weakly acidic chloride solution of 750r111.

Chlorine gas was introduced into the slurry at a rate of 2.5 grams per minute.

After 14 minutes, the chlorine flow was stopped and analysis of the leaching solution showed a nickel content of 15 Fl/A and a copper content of 10.99/l, indicating that precipitation had occurred during the leaching.

The residue does not contain elemental sulfur and is partially leached matte with an analysis value of 58.3% Nickel, 8.5% Copper, 8.5% Sulfur, and 30.9 by weight.
．． ! 9 (measured after washing with heated toluene).

The percentage of nickel leached from the initial mat was 31%.

This partially leached mat was used for copper precipitation as follows.

150 g of partially leached matte were added at 90° C. to 750 ml of acidified sulphated steel solution containing 109,713 copper.

The slurry was stirred and sampled at 30 minute intervals.

The copper content at that time is shown in Table 1 below.

For comparison, the results are also shown when the precipitation was carried out in the manner described above, except that instead of the partially leached matte, the initial, ie, unleached, as-granulated matte was used.

Thus, in the precipitation carried out according to the method of the present invention, 30
It can be seen that the copper level in the solution after 90 minutes was reduced compared to the results after 90 minutes for precipitation with unactivated mats.

Example 2 A nickel extraction test was carried out using the same mat that constituted the starting material in Example 1.

97.5g of the first sample (55g) of this mat
In 750 rrtl of an acidified solution containing nickel/l and 9.09/11 copper, the temperature was raised to 92-103°C and chlorine was passed through the slurry at a rate of 1.6 grams per minute for 30 minutes. Chlorine was leached out by foaming.

A second portion of the same matte (95 grams) was added to the slurry and the chlorine flow was continued for an additional 40 minutes. This period allowed the second portion of the matte to dissolve only partially leached, dissolving 60% of the nickel present. It was sufficient.

The chlorine flow was then discontinued and a residual sample was removed for analysis.

The slurry was kept stirring and the copper level in the solution was measured at regular intervals.

The precipitation results are shown in Table 2 below.

A preliminary test residue sample taken after 70 minutes of leaching was washed with heated toluene to remove elemental sulfur present in the leaching of the first part of the mat, and then analyzed for nickel and sulfur. did.

The atomic ratio of nickel to sulfur is 0.55, and
One line diffraction test showed the absence of any Ni3S2 phase.

From this it can be seen that the nickel sulfide that acts as a precipitant from the point at which chlorine leaching is stopped is a matte with an Ni/S atomic ratio considerably lower than 1.

Example 3 This example illustrates the practical application of the precipitation method of the present invention for the recovery of nickel from nickel mattes.

The first stage leached 2,000 grams of granulated matte with an analytical value of nickel: 77.2%, copper: 0.49%, cobalt: 1.19%, iron: o, so%, sulfur: 19.4%. ,
At a temperature of 60°C, 1609/l of nickel and 4-09
8.6 liters of chloride solution containing copper/l.

3 by passing chlorine through the slurry at a rate of 207 i/min.
The slurry was bubbled for 0 minutes during which time the temperature of the slurry was raised to the boiling point (110° C.).

The chlorine flow was discontinued and the partially leached matte slurry, in which 30% of the nickel had been leached, was stirred for an additional 105 minutes to cause copper precipitation.

The solution was then filtered and contained 250 g/l) nickel and 0.379 g/l) copper.

After purification by conventional means, this solution was used for electrowinning of nickel.

Second stage leaching 8.2 liters of electrolyte used from the electrowinning operation containing nickel of 5.5 &/13 mm and no copper, containing 160 g/l of nickel and 41/l of copper. Mixed with 1.9 liters of chloride solution.

The solid residue of the first stage leaching (15749) was added to this solution at 74° C. and pH 1.5.

The slurry was then stirred and chlorine was introduced at a rate of 20.9/min.

Chlorine was absorbed quantitatively over 68 minutes.

At this point, the chlorine in the off-gases clearly indicated the end of the reaction, so the chlorine flow rate was reduced to 50 parts and stopped after a few more minutes.

During leaching, the slurry temperature rose to boiling point, but at the end of the reaction the slurry began to cool.

The slurry was filtered, and the residue (382, l) was basically sulfur, which was analyzed by weight: Copper: 0.15% Nickel: 1.16%, Cobalt: 0.09% Iron: 0 .55% Sulfur: 97.4%.

The resulting filtrate can then be recycled to carry out the first stage leaching on a new sample of matte, with appropriate adjustment of its copper content if necessary.

Reference is made here to copper-containing solutions treated with activated (i.e. partially chlorine-leached) nickel mattes, and such mattes are not necessarily activated prior to addition to the copper-containing solution. It will be clear from the specific embodiments described above that this is not necessary.

Claims (1)

[Claims] 1. 15 to 60% of nickel is leached from the matte by reacting a mud slurry in an aqueous solution containing copper ions with gaseous chlorine, and the partially leached matte is further converted into a gaseous state. A method of precipitating copper from an aqueous solution by means of a nickel mat, in which the copper is brought into contact with the solution in which it is precipitated without contact with the chlorine. 2. Treatment of a solution containing nickel and copper resulting from contacting a copper ion-containing aqueous slurry of a nickel matte containing at least 10 ji/l of dissolved copper with chlorine such that some or all of the nickel is dissolved from the matte. A method according to claim 1 applied to. 3. Slurry the matte with an aqueous solution containing at least 109/l of copper, introduce chlorine into the slurry so that the nickel in the matte migrates into the solution, and add chlorine to the slurry for 15 to 15 minutes.
Once 60% of nickel has been leached from the matte, the resulting partially leached matte is kept in contact with the nickel and copper-containing leaching solution to allow the copper to precipitate out of solution, and the precipitated copper and 3. The method of claim 2, wherein nickel is recovered from the nickel matte by separating the leaching residue from the solution. 4. Claims for dividing the mat into two or more parts, fully leaching the first part, and then adding other parts and only partially leaching to remove 15-60% of the nickel therefrom. The method described in Section 2. 5. A method according to any of claims 2 to 4, wherein the copper-containing solution contains at least 3 CJ9//J of copper. 6. The method of claim 3, comprising the steps of subjecting the precipitated copper, the separated solution and the leaching residue to purification, and recovering pure nickel therefrom by electrowinning. 7. Mixing the spent electrolyte from the electrowinning process with the precipitated copper and leaching residue, and treating the mixture with chlorine in an amount sufficient to ensure dissolution of the precipitated copper and substantially complete leaching of the leaching residue. 7. The method of claim 6, including the step of treating the solids to obtain a slurry consisting essentially of sulfur.